The invention relates to an optical assembly having retaining means and at least one optical element retained thereby.
Such an assembly, which may also be referred to as "optical device", is known from French Patent Specification No. 430,551. The known optical assembly is intended for use in projection apparatus and comprises two optical lenses and three leaf springs clamped between an inner and an outer ring. The leaf springs comprise hook-shaped end portions which engage around the lens peripheries in order to keep the lenses in a specific position relative to each other.
A drawback of the known assembly is that for retaining the lenses a large number of parts are required which are secured to each other in a specific position relative to one another. Further, it is to be noted that the lenses are retained by means of a clamping force, the clamping force of the leaf spring and the friction between the leaf springs and the lenses playing an essential part. Such a construction has the drawback that the friction which occurs gives rise to a specific positional inaccuracy. This inaccuracy, also referred to as "virtual play" by those skilled in the art, renders the known construction unsuitable for retaining optical elements at a predetermined location and in a predetermined position with an accuracy in the sub-micron range.